1. Field of the Invention
This invention relates to a water-metachromatic cloth sheet, a toy set making use of the same and a writing instrument for water-metachromatic members. More particularly, it relates to a water-metachromatic cloth sheet capable of assuming different aspects depending on whether it stands dry or stands wet with water, a toy set making use of such a sheet, and a convenient writing instrument for water-metachromatic members which enable formation of any desired handwriting images by means of water, on water-metachromatic members capable of assuming such alternately changeable aspects.
In the present invention, a white or colored opaque sheet turns colorless or transparent, and vice versa, depending on whether it is dry or wet. This is also regarded as a change in color, i.e., metachromatism.
2. Related Background Art
Sheets comprising a support and provided thereon a porous layer containing a pigment having a low refractive index, to the porous layer of which water is made to adhere to make it transparent to cause an image to appear, are conventionally known as disclosed in Japanese Patent Publications No. Sho50-5097 and No. Hei5-15389.
As fields to which such sheets are chiefly applied, they are conventionally applied to practice of calligraphy, image appearing-disappearing toys and so forth, and are mostly comprised of paper as the support or substrate, having a poor durability.
U.S. Pat. No. 5,163,846 discloses a water-reactive sheet of this type and a water pen with which one can write on the sheet, but does not disclose any specific construction of water pens that can satisfy practical usability.